Noticed that serial crasher was being given conflicting advice, like:

Cut the prop to the required size.
Don't cut a prop.
Balance it. Scrape the tip. Scrape the back.
Don't balance, use the prop as it is...
Etc.

The fact is:
Modifying a prop should NOT be done by anyone except an expert on the subject.
The tip of a 6" dia prop on a 2200kv motor on a 3s lipo is doing about 600 kmph
Imagine the effect of even slight modifications!

However, all props must be balanced.
If you can, get a magnetic balancer (rather expensive)
Or get a hand held balancer (cheaper)
If without access to either, locate a dowel that fits the hole in the prop.
You could use a knitting needle or a drill bit.
You can even get reed dowels from the base of flower bouquets. Find one that fits the prop firmly.
Balance it on the edge of two equal height glasses/tins/katories.
Add weight to the lighter blade BY SPRAYING CLEAR LAQUER OR PAINT on the rear side.
You could even use nail polish and a brush.
Wait till the thinner has evaporated and check again.
Once you hear the sweet sound of a balanced prop, you'll know it was worth the effort!

  No sure about others, but now I realized the value of a balanced prop. This is an amazingly simple way to balance. Many thanks.

These tip & Tricks has the potential take someone a long way in this hobby.

... else like an unbalanced prop we may make a lot of noise and destroy our own planes and blame the hobby being not a forgiving.

 one.

Thats true. Balanced props always have far better performance as compared to unbalanced ones. But, yeah one has to be patient and give proper time while doing this to have best results. Before, I was doing this by keeping my props hanging between books through a rod . But, now I am myself making a prop balancer. Just searching for a better light weight iron rod that could hang on my magnet bars. It would be some what like this.(got it on a thread here)

Thanks Mr. Iyer this is good advise. Will be trying it out 

@ K K Iyer ..... Great piece of info ...

prop balancing